AC Drives: Line and Load Reactors: Can They Improve the Performance
of Variable-Frequency Drive Systems?

Three-phase harmonic-compensatedline
or load reactors allow one to "clean
up" the voltage being sent to the motor from a VFD (Variable-Frequency
Drive). Harmonic compensation maximizes the reactor's benefit to the VFD
input circuit, while
PWM / IGBT protection maximizes their performance in the drive
output circuit. A purer voltage to both the VFD and the motor means:

Improved Motor Drive System Reliability

Reduced Motor Drive System Downtime

Improved True Power Factor

Virtual Elimination of Inverter Nuisance Tripping

Attenuation of Input Current Harmonics

Extended Motor Life

Reduced Motor Peak Voltage

Reduced Motor dv/dt Spikes

Reduced Motor Temperature

Reduced Motor Noise

Difference between
"line" and "load" reactors:

Line reactors are used the "line side" or input of a variable
frequency drive (i.e. where three-phase voltage comes into the VFD). The
following schematic shows a line-reactor installation in a VFD system:

Load reactors are used on the "load" side of variable frequency
drive (between the drive and the motor). Load reactors are a new, more
effective reactor technology and are ideal for harmonic compensation.
The following schematic shows a load-reactor installation in a VFD system:

About Harmonics

Harmonics, or multiple frequencies of the original, are always present
on the supply and com from many different types of equipment connected
to the supply. Some harmonics are introduced by iron cored components
such as motors and transformers, but by far the greatest source
of harmonics are electronic rectifiers as found in inverters and switched-mode
power supplies.